CA2170922C - Compound semiconductor light emitting device and method of preparing the same - Google Patents
Compound semiconductor light emitting device and method of preparing the same Download PDFInfo
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- CA2170922C CA2170922C CA002170922A CA2170922A CA2170922C CA 2170922 C CA2170922 C CA 2170922C CA 002170922 A CA002170922 A CA 002170922A CA 2170922 A CA2170922 A CA 2170922A CA 2170922 C CA2170922 C CA 2170922C
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 42
- 150000001875 compounds Chemical class 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 37
- 239000000758 substrate Substances 0.000 claims abstract description 74
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims abstract description 26
- 238000000927 vapour-phase epitaxy Methods 0.000 claims abstract description 19
- 229910005540 GaP Inorganic materials 0.000 claims abstract description 12
- 229910000673 Indium arsenide Inorganic materials 0.000 claims abstract description 12
- RPQDHPTXJYYUPQ-UHFFFAOYSA-N indium arsenide Chemical compound [In]#[As] RPQDHPTXJYYUPQ-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052782 aluminium Inorganic materials 0.000 claims abstract 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 37
- 238000006243 chemical reaction Methods 0.000 claims description 26
- 239000007789 gas Substances 0.000 claims description 17
- 239000002994 raw material Substances 0.000 claims description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 14
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims description 14
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims description 14
- 229910021529 ammonia Inorganic materials 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims description 6
- 229910052733 gallium Inorganic materials 0.000 claims description 6
- 229910052738 indium Inorganic materials 0.000 claims description 3
- 229910001510 metal chloride Inorganic materials 0.000 abstract description 7
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 75
- 229910002601 GaN Inorganic materials 0.000 description 73
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 26
- XCZXGTMEAKBVPV-UHFFFAOYSA-N trimethylgallium Chemical compound C[Ga](C)C XCZXGTMEAKBVPV-UHFFFAOYSA-N 0.000 description 23
- 235000012431 wafers Nutrition 0.000 description 19
- 229910052594 sapphire Inorganic materials 0.000 description 16
- 239000010980 sapphire Substances 0.000 description 16
- IBEFSUTVZWZJEL-UHFFFAOYSA-N trimethylindium Chemical compound C[In](C)C IBEFSUTVZWZJEL-UHFFFAOYSA-N 0.000 description 14
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 8
- 239000002019 doping agent Substances 0.000 description 6
- 238000000407 epitaxy Methods 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 229910052717 sulfur Inorganic materials 0.000 description 6
- 239000011701 zinc Substances 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 238000000171 gas-source molecular beam epitaxy Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 150000004678 hydrides Chemical class 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- RGGPNXQUMRMPRA-UHFFFAOYSA-N triethylgallium Chemical compound CC[Ga](CC)CC RGGPNXQUMRMPRA-UHFFFAOYSA-N 0.000 description 3
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 229910052785 arsenic Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 125000005842 heteroatom Chemical group 0.000 description 2
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000012808 vapor phase Substances 0.000 description 2
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000000295 emission spectrum Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000002040 relaxant effect Effects 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/26—Materials of the light emitting region
- H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
- H01L33/32—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table containing nitrogen
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/005—Processes
- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
- H01L33/0075—Processes for devices with an active region comprising only III-V compounds comprising nitride compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S438/00—Semiconductor device manufacturing: process
- Y10S438/914—Doping
- Y10S438/925—Fluid growth doping control, e.g. delta doping
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Led Devices (AREA)
Abstract
A high performance compound semiconductor light emitting device and a method which can industrially prepare the same are provided. The compound semiconductor light emitting device includes a GaAs, GaP, InAs or InP
substrate, a buffer layer consisting of GaN, having a thickness of 10 nm to 80 nm, which is formed on the substrate, an epitaxial layer consisting of Al x Ga1-x N(0 ~ x < 1) which is formed on the buffer layer, an incommensurate plane which is located on the interface between the buffer layer and the epitaxial layer, a light emitting layer which is formed on the epitaxial layer, and a clad layer which is formed on the light emitting layer. The buffer layer is formed by organic metal chloride vapor phase epitaxy at a first temperature, while the epitaxial layer is formed by organic metal chloride vapor phase epitaxy at a second temperature which is higher than the first temperature.
The light emitting layer preferably consists of In y Ga1-y N(0< y < 1) which is doped with Mg.
substrate, a buffer layer consisting of GaN, having a thickness of 10 nm to 80 nm, which is formed on the substrate, an epitaxial layer consisting of Al x Ga1-x N(0 ~ x < 1) which is formed on the buffer layer, an incommensurate plane which is located on the interface between the buffer layer and the epitaxial layer, a light emitting layer which is formed on the epitaxial layer, and a clad layer which is formed on the light emitting layer. The buffer layer is formed by organic metal chloride vapor phase epitaxy at a first temperature, while the epitaxial layer is formed by organic metal chloride vapor phase epitaxy at a second temperature which is higher than the first temperature.
The light emitting layer preferably consists of In y Ga1-y N(0< y < 1) which is doped with Mg.
Description
COMPOUND SEMICONDUCTOR LIGHT EMITTING DEVICE AND METHOD
OF PREPARING THE SAME
The present invention relates to a compound semiconductor light emitting device and a method of preparing the same, and more particularly, it relates to a GaN
compound semiconductor light emitting device employing a substrate of GaAs, GaP, InAs or InP and a method of preparing the same.
Figure 5 is a sectional view showing the structure of a blue and green light emitting device (LED) employing a sapphire substrate, described in Nikkei Science, October 1994, P. 44, for example, which is now available on the market.
Referring to Figure 5, a clad layer 14, a light emitting layer 15, a clad layer 16 and a GaN epitaxial layer 17 are successively formed on an epitaxial wafer which is formed by a sapphire substrate 11, a gallium nitride (GaN) buffer layer 12 formed on the substrate 11, and a hexagonal GaN epitaxial layer 13 formed on the GaN
buffer layer 12 in this blue and green light emitting device, while ohmic electrodes 18 and 19 are formed on the GaN epitaxial layers 13 and 17 respectively. In this blue and green light emitting device, the GaN buffer layer 12 is adapted to relax distortion resulting from the difference between lattice constants of the sapphire substrate 11 and the GaN epitaxial layer 13.
Referring to Figure 5, this blue and green light emitting device employs insulating sapphire as the material for the substrate 11, and hence two types of electrodes must be formed on the same surface side, in order to prepare the device with formation of the electrodes. Thus, patterning by photolithography must be performed at least twice and the nitride layer must be etched by reactive ion etching, leading to a requirement for complicated steps. Further, the substrate is hard to treat in element isolation, due to the hardness of sapphire. Further, in application of the light emitting device, the sapphire substrate is disadvantageously inapplicable to a laser diode having an optical resonator defined by a cleavage plane, because sapphire is uncleavable.
In a conventional growth method, on the other hand, the growth temperature is so high that growth of a high Indium (In) composition ratio cannot be
OF PREPARING THE SAME
The present invention relates to a compound semiconductor light emitting device and a method of preparing the same, and more particularly, it relates to a GaN
compound semiconductor light emitting device employing a substrate of GaAs, GaP, InAs or InP and a method of preparing the same.
Figure 5 is a sectional view showing the structure of a blue and green light emitting device (LED) employing a sapphire substrate, described in Nikkei Science, October 1994, P. 44, for example, which is now available on the market.
Referring to Figure 5, a clad layer 14, a light emitting layer 15, a clad layer 16 and a GaN epitaxial layer 17 are successively formed on an epitaxial wafer which is formed by a sapphire substrate 11, a gallium nitride (GaN) buffer layer 12 formed on the substrate 11, and a hexagonal GaN epitaxial layer 13 formed on the GaN
buffer layer 12 in this blue and green light emitting device, while ohmic electrodes 18 and 19 are formed on the GaN epitaxial layers 13 and 17 respectively. In this blue and green light emitting device, the GaN buffer layer 12 is adapted to relax distortion resulting from the difference between lattice constants of the sapphire substrate 11 and the GaN epitaxial layer 13.
Referring to Figure 5, this blue and green light emitting device employs insulating sapphire as the material for the substrate 11, and hence two types of electrodes must be formed on the same surface side, in order to prepare the device with formation of the electrodes. Thus, patterning by photolithography must be performed at least twice and the nitride layer must be etched by reactive ion etching, leading to a requirement for complicated steps. Further, the substrate is hard to treat in element isolation, due to the hardness of sapphire. Further, in application of the light emitting device, the sapphire substrate is disadvantageously inapplicable to a laser diode having an optical resonator defined by a cleavage plane, because sapphire is uncleavable.
In a conventional growth method, on the other hand, the growth temperature is so high that growth of a high Indium (In) composition ratio cannot be
2 attained in an InGaN layer which is an active layer, and hence a blue-green light emitting device is hard to prepare. Further, introduction of zinc (Zn) for serving as an emission center is inevitably required, leading to technical problems in application as a device such that the emission wavelength is broad and thus performance in full color display is deteriorated.
To this end, an attempt has been made to employ conductive GaAs as the material for the substrate in place of sapphire having the aforementioned disadvantages. When the substrate is prepared from GaAs, however, an epitaxial wafer which rivals that employing the sapphire substrate cannot be obtained under conditions similar to those for the case of employing the sapphire substrate.
In relation to preparation of an epitaxial wafer with a GaAs substrate, therefore, various studies have been conducted in the art.
Among these studies, Nihon Kessho Seicho Gakkai-Shi Vol. 21, No. 5 (1994), Supplement S409 to S414 (hereinafter referred to as "reference 1"), for example, discloses an epitaxial wafer as shown in Figure 6.
Referring to Figure 6, this epitaxial wafer comprises a GaAs substrate 21, a GaAs buffer layer 22 which is formed on the substrate 21, a GaN coating 23 which is obtained by nitriding a surface of the GaAs buffer layer 22 thereby replacing arsenic (As) with nitrogen (N), and a GaN epitaxial layer 24 which is formed on the GaN
coating 23.
In preparation of this epitaxial wafer, the GaN epitaxial layer 24 is formed by OMVPE (organic metal vapor phase epitaxy). This OMVPE is adapted to grow a GaN epitaxial layer on a substrate in a vapor phase by introducing a first gas including trimethylgallium (TMGa) and a second gas including ammonia (NH3) into a reaction chamber while heating only the substrate in the reaction chamber by high-frequency heating.
On the other hand, Jpn. J. Appl. Phys. Vol. 33 (1994) pp. 1747-1752 (hereinafter referred to as "reference 2"), for example, discloses an epitaxial wafer shown in Figure 7.
To this end, an attempt has been made to employ conductive GaAs as the material for the substrate in place of sapphire having the aforementioned disadvantages. When the substrate is prepared from GaAs, however, an epitaxial wafer which rivals that employing the sapphire substrate cannot be obtained under conditions similar to those for the case of employing the sapphire substrate.
In relation to preparation of an epitaxial wafer with a GaAs substrate, therefore, various studies have been conducted in the art.
Among these studies, Nihon Kessho Seicho Gakkai-Shi Vol. 21, No. 5 (1994), Supplement S409 to S414 (hereinafter referred to as "reference 1"), for example, discloses an epitaxial wafer as shown in Figure 6.
Referring to Figure 6, this epitaxial wafer comprises a GaAs substrate 21, a GaAs buffer layer 22 which is formed on the substrate 21, a GaN coating 23 which is obtained by nitriding a surface of the GaAs buffer layer 22 thereby replacing arsenic (As) with nitrogen (N), and a GaN epitaxial layer 24 which is formed on the GaN
coating 23.
In preparation of this epitaxial wafer, the GaN epitaxial layer 24 is formed by OMVPE (organic metal vapor phase epitaxy). This OMVPE is adapted to grow a GaN epitaxial layer on a substrate in a vapor phase by introducing a first gas including trimethylgallium (TMGa) and a second gas including ammonia (NH3) into a reaction chamber while heating only the substrate in the reaction chamber by high-frequency heating.
On the other hand, Jpn. J. Appl. Phys. Vol. 33 (1994) pp. 1747-1752 (hereinafter referred to as "reference 2"), for example, discloses an epitaxial wafer shown in Figure 7.
3 Referring to Figure 7, a cubic GaN epitaxial layer 33 is formed on a substrate 31 which is previously provided on its surface with a cubic GaN
buffer layer 32 by GS-MBE (gas source molecular beam epitaxy).
In preparation of the epitaxial wafer, the GaN epitaxial layer 33 is formed by hydride VPE (vapor phase epitaxy). This hydride VPE is adapted to set a substrate and a source boat containing Ga metal in a reaction chamber and to introduce a first gas including hydrogen chloride (HCI) and a second gas including ammonia (NH3) into the reaction chamber while heating the overall reaction chamber with a resistance heater from the exterior, thereby growing a GaN epitaxial layer on the substrate in a vapor phase.
In the epitaxial wafer disclosed in reference 1, however, the GaN epitaxial layer is grown by the OMVPE, as described above. When the GaN epitaxial layer is grown on the GaAs substrate by the OMVPE, the film growth rate is extremely low as compared to growing the layer on a sapphire substrate. In more concrete terms, the film forming rate for forming a film on a GaAs substrate is about 0.15 ~cm/h., while a film forming rate of about 3 ,um/h. is attained in the case of forming a film on a sapphire substrate under the same conditions. For example, a GaN epitaxial layer of about 4 ,um in thickness must be formed in order to apply the epitaxial wafer to a light emitting device, which therefore requires almost one day for preparation using this method. Thus, preparation of an epitaxial wafer by this method is unsuitable for industrialization, due to production time and cost.
Further, according to this method, the treatment temperature for growing the GaN epitaxial layer cannot be increased. Therefore, improvement of the characteristics of the obtained GaN epitaxial layer is limited.
In the OMVPE, ammonia is not sufFciently decomposed due to the so-called cold wall method of heating only the substrate in the reaction chamber.
Thus, it is necessary to increase the supply quantity of ammonia in order to compensate for the undecomposability, leading to a high VIII ratio (the ratio of a group V
raw material to a group III raw material) of raw material supply.
buffer layer 32 by GS-MBE (gas source molecular beam epitaxy).
In preparation of the epitaxial wafer, the GaN epitaxial layer 33 is formed by hydride VPE (vapor phase epitaxy). This hydride VPE is adapted to set a substrate and a source boat containing Ga metal in a reaction chamber and to introduce a first gas including hydrogen chloride (HCI) and a second gas including ammonia (NH3) into the reaction chamber while heating the overall reaction chamber with a resistance heater from the exterior, thereby growing a GaN epitaxial layer on the substrate in a vapor phase.
In the epitaxial wafer disclosed in reference 1, however, the GaN epitaxial layer is grown by the OMVPE, as described above. When the GaN epitaxial layer is grown on the GaAs substrate by the OMVPE, the film growth rate is extremely low as compared to growing the layer on a sapphire substrate. In more concrete terms, the film forming rate for forming a film on a GaAs substrate is about 0.15 ~cm/h., while a film forming rate of about 3 ,um/h. is attained in the case of forming a film on a sapphire substrate under the same conditions. For example, a GaN epitaxial layer of about 4 ,um in thickness must be formed in order to apply the epitaxial wafer to a light emitting device, which therefore requires almost one day for preparation using this method. Thus, preparation of an epitaxial wafer by this method is unsuitable for industrialization, due to production time and cost.
Further, according to this method, the treatment temperature for growing the GaN epitaxial layer cannot be increased. Therefore, improvement of the characteristics of the obtained GaN epitaxial layer is limited.
In the OMVPE, ammonia is not sufFciently decomposed due to the so-called cold wall method of heating only the substrate in the reaction chamber.
Thus, it is necessary to increase the supply quantity of ammonia in order to compensate for the undecomposability, leading to a high VIII ratio (the ratio of a group V
raw material to a group III raw material) of raw material supply.
4 According to Appl. Phys. Lett. 64 (1994), p. 1687, for example, it is calculated from the values of quantities of raw material introduction in growth that the VIII ratio in GaN growth on a sapphire substrate is up to 6.0 x 103 and that in GaInN
growth is up to 1.1 x 104. Thus, the OPMVPE leads to enormous raw material consumption, and hence an epitaxial wafer cannot be prepared at a low cost.
Additionally, according to the OMVPE, epitaxy is made at a high temperature of at least 800°C, in order to facilitate decomposition of ammonia which is employed as the group V raw material. When the growth rate is thus increased, however, a GaInN layer of high indium (In) composition is hard to form, as described above.
In the epitaxial wafer disclosed in reference 2, on the other hand, a substrate must be prepared which has been previously provided with a GaN
buffer on its surface by GS-MBE, in order to form a GaN epitaxial layer. In this case, the growth rate is so slow that formation of the GaN buffer layer on the GaAs substrate by GS-MBE is not practical for industrialization.
Due to employment of the hydride VPE, hetero growth requiring a plurality of sources as well as growth of a number of layers are so difficult that this method is unsuitable for industrial application. In addition, two reaction chambers are required for preparing an epitaxial wafer by this method since a buffer layer and an epitaxial layer are grown by different methods, and hence surface contamination caused by interruption of growth may disadvantageously interfere in the process.
Further, in reference 2, preparation conditions etc. for obtaining a GaN
epitaxial layer of high quality/characteristics have not been studied in particular.
An object of the present invention is to provide a high performance compound semiconductor light emitting device solving the aforementioned problems and a method which can industrially prepare the same.
According to an aspect of the present invention, a compound semiconductor light emitting device is provided. This compound semiconductor light emitting diode includes a substrate of a compound semiconductor which is selected from a group consisting of GaAs, GaP, InAs and InP, a buffer layer consisting of GaN, having a thickness of 10 nm to 80 nm, which is formed on the substrate, an epitaxial layer consisting of AIXGa,_xN (0 <_ x < 1 ) which is formed on the buffer layer, an incommensurate plane which is located on the interface between the buffer layer and the epitaxial layer, a light emitting layer which is formed on the epitaxial layer, and a
growth is up to 1.1 x 104. Thus, the OPMVPE leads to enormous raw material consumption, and hence an epitaxial wafer cannot be prepared at a low cost.
Additionally, according to the OMVPE, epitaxy is made at a high temperature of at least 800°C, in order to facilitate decomposition of ammonia which is employed as the group V raw material. When the growth rate is thus increased, however, a GaInN layer of high indium (In) composition is hard to form, as described above.
In the epitaxial wafer disclosed in reference 2, on the other hand, a substrate must be prepared which has been previously provided with a GaN
buffer on its surface by GS-MBE, in order to form a GaN epitaxial layer. In this case, the growth rate is so slow that formation of the GaN buffer layer on the GaAs substrate by GS-MBE is not practical for industrialization.
Due to employment of the hydride VPE, hetero growth requiring a plurality of sources as well as growth of a number of layers are so difficult that this method is unsuitable for industrial application. In addition, two reaction chambers are required for preparing an epitaxial wafer by this method since a buffer layer and an epitaxial layer are grown by different methods, and hence surface contamination caused by interruption of growth may disadvantageously interfere in the process.
Further, in reference 2, preparation conditions etc. for obtaining a GaN
epitaxial layer of high quality/characteristics have not been studied in particular.
An object of the present invention is to provide a high performance compound semiconductor light emitting device solving the aforementioned problems and a method which can industrially prepare the same.
According to an aspect of the present invention, a compound semiconductor light emitting device is provided. This compound semiconductor light emitting diode includes a substrate of a compound semiconductor which is selected from a group consisting of GaAs, GaP, InAs and InP, a buffer layer consisting of GaN, having a thickness of 10 nm to 80 nm, which is formed on the substrate, an epitaxial layer consisting of AIXGa,_xN (0 <_ x < 1 ) which is formed on the buffer layer, an incommensurate plane which is located on the interface between the buffer layer and the epitaxial layer, a light emitting layer which is formed on the epitaxial layer, and a
5 clad layer which is formed on the light emitting layer.
The incommensurate plane which is located on the interface between the buffer layer and the epitaxial layer may conceivably result from deviation of crystal lattices caused by the difference between growth temperatures of the buffer layer and the epitaxial layer, for example. This incommensurate plane can be observed as the difference in contrast between the buffer layer and the epitaxial layerthrough sectional observation with a transmission electron microscope.
In the compound semiconductor light emitting device, preferably the epitaxial layer consists of AIXGa,_XN (0 s x < 1 ) having a first conductivity type, the light emitting layer consists of InyGa,_yN (0 < y < 1 ), and the clad layer consists of AIZGa,_ZN
(0 s z < 1 ) having a second conductivity type which is different from the first conductivity type.
When the light emitting layer consisting of InyGa,_yN is not doped with an emission center such as Zn, band-edge emission of luminescent colors of violet, blue, green and yellow, i.e., sharp emission spectra, are obtained in the ranges of 0 < y <
0.4, 0.4 s y < 0.7, 0.7 s y < 0.9 and 0.9 s y < 1 respectively.
Preferably, the light emitting layer consisting of InyGa,_yN is doped with Mg.
Further preferably, the thickness of the buffer layer is 20 nm to 60 nm in the compound semiconductor light emitting device.
According to another aspect of the present invention, a method of preparing a compound semiconductor light emitting device is provided. This method comprises the steps of forming a buffer layer consisting of GaN on a substrate of a compound semiconductor which is selected from a group consisting of GaAs, GaP, InAs and InP
at a first temperature by a method of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into a reaction chamber while heating the overall reaction chamber from the
The incommensurate plane which is located on the interface between the buffer layer and the epitaxial layer may conceivably result from deviation of crystal lattices caused by the difference between growth temperatures of the buffer layer and the epitaxial layer, for example. This incommensurate plane can be observed as the difference in contrast between the buffer layer and the epitaxial layerthrough sectional observation with a transmission electron microscope.
In the compound semiconductor light emitting device, preferably the epitaxial layer consists of AIXGa,_XN (0 s x < 1 ) having a first conductivity type, the light emitting layer consists of InyGa,_yN (0 < y < 1 ), and the clad layer consists of AIZGa,_ZN
(0 s z < 1 ) having a second conductivity type which is different from the first conductivity type.
When the light emitting layer consisting of InyGa,_yN is not doped with an emission center such as Zn, band-edge emission of luminescent colors of violet, blue, green and yellow, i.e., sharp emission spectra, are obtained in the ranges of 0 < y <
0.4, 0.4 s y < 0.7, 0.7 s y < 0.9 and 0.9 s y < 1 respectively.
Preferably, the light emitting layer consisting of InyGa,_yN is doped with Mg.
Further preferably, the thickness of the buffer layer is 20 nm to 60 nm in the compound semiconductor light emitting device.
According to another aspect of the present invention, a method of preparing a compound semiconductor light emitting device is provided. This method comprises the steps of forming a buffer layer consisting of GaN on a substrate of a compound semiconductor which is selected from a group consisting of GaAs, GaP, InAs and InP
at a first temperature by a method of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into a reaction chamber while heating the overall reaction chamber from the
6 exterior for making vapor phase epitaxy on the substrate which is set in the reaction chamber, forming an epitaxial layer consisting of AIXGa,_xN (0 <_ x < 1 ) on the buffer layer at a temperature which is higher than the first temperature by the method of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into the reaction chamber while heating the overall reaction chamber from the exterior for making vapor phase epitaxy on the substrate which is set in the reaction chamber, forming a light emitting layer on the epitaxial layer, and forming a clad layer on the light emitting layer.
The organic metal raw material containing gallium is prepared from trimethylgallium or triethylgallium, for example.
In the method of preparing a compound semiconductor light emitting device, preferably the epitaxial layer consists of AIXGa,_XN (0 s x < 1 ) having a first conductivity type, the light emitting layer consists of InyGa,_yN (0 < y < 1 ), and the clad layer consists of AIZGa,_ZN (0 s z < 1 ) having a second conductivity type which is different from the first conductivity type.
Preferably, the light emitting layer consisting of InYGa,_yN is doped with Mg.
Further preferably, the first temperature is 300°C to 700°C
and the second temperature is at least 750°C in the method of preparing a compound semiconductor light emitting device.
More preferably, the first temperature is 400°C to 600°C.
The compound semiconductor light emitting device according to the present invention has a buffer layer consisting of GaN having a thickness of 10 nm to 80 nm.
While the conventional blue and green light emitting device employing a sapphire substrate is also provided with a buffer layer consisting of GaN, this buffer layer is mainly adapted to relax distortion caused by the difference between the lattice constants of the sapphire substrate and the GaN epitaxial layer. On the other hand, the buffer layer provided in the present invention also serves as a heat-resistant coating, in addition to the function of relaxing distortion.
While GaN must be epitaxially grown at an extremely high temperature of 800°C to 1100°C in general, GaN and the sapphire substrate are not thermally
The organic metal raw material containing gallium is prepared from trimethylgallium or triethylgallium, for example.
In the method of preparing a compound semiconductor light emitting device, preferably the epitaxial layer consists of AIXGa,_XN (0 s x < 1 ) having a first conductivity type, the light emitting layer consists of InyGa,_yN (0 < y < 1 ), and the clad layer consists of AIZGa,_ZN (0 s z < 1 ) having a second conductivity type which is different from the first conductivity type.
Preferably, the light emitting layer consisting of InYGa,_yN is doped with Mg.
Further preferably, the first temperature is 300°C to 700°C
and the second temperature is at least 750°C in the method of preparing a compound semiconductor light emitting device.
More preferably, the first temperature is 400°C to 600°C.
The compound semiconductor light emitting device according to the present invention has a buffer layer consisting of GaN having a thickness of 10 nm to 80 nm.
While the conventional blue and green light emitting device employing a sapphire substrate is also provided with a buffer layer consisting of GaN, this buffer layer is mainly adapted to relax distortion caused by the difference between the lattice constants of the sapphire substrate and the GaN epitaxial layer. On the other hand, the buffer layer provided in the present invention also serves as a heat-resistant coating, in addition to the function of relaxing distortion.
While GaN must be epitaxially grown at an extremely high temperature of 800°C to 1100°C in general, GaN and the sapphire substrate are not thermally
7 damaged by such a high temperature exceeding 800°C. However, a substrate of GaAs, GaP, InAs or InP cannot serve as a substrate at a high temperature exceeding 800°C, since As or P is lost. In order to form a GaN epitaxial layer on a substrate of GaAs, GaP, InAs or InP, therefore, it is necessary to provide a heat-resistant coating.
According to the present invention, the gaN buffer layer which is formed at a lower temperature than the gaN epitaxial layer serves as such a heat-resistant coating.
The thickness of this GaN buffer layer is 10 nm to 80 nm. If the thickness is smaller than 10 nm, the buffer layer is partially broken during temperature increase for forming the epitaxial layer, to inevitably separate the epitaxial layer which is formed thereon. If the thickness is larger than 80 nm, on the other hand, nuclear growth is mixed into low-temperature growth of a flat buffer layer, to disadvantageously grow the epitaxial layer in the form of a pyramid about such nucleus.
According to the present invention, band-edge emission can be implemented when the light emitting layer consists of InyGa,_yN (0 < y < 1) which is doped with Mg.
In the conventional blue and green light emitting device, the emission wavelength is broad since blue emission is attained by introducing a deep center of Zn as an emission center. According to the present invention, on the other hand, formation of a GaInN layer of high In composition is enabled by employing a substrate of GaAs, GaP, InAs or InP. Consequently, band-edge emission having a sharp emission wavelength can be implemented by Mg doping, thereby enabling wide-ranging application to a laser diode and the like.
According to the inventive method of preparing a compound semiconductor light emitting device, the GaN buffer layer is formed on the substrate of the compound semiconductor which is selected from the group consisting of GaAs, GaP, InAs and InP at a temperature lower than the growth temperature of the GaN epitaxial layer.
Therefore, a cubic GaN epitaxial layer of high quality can be grown with no damage on the substrate crystals.
The temperature for forming the buffer layer consisting of GaN is preferably 300°C to 700°C. If the temperature is lower than 300°C, no buffer layer consisting of GaN is grown. If the temperature is higher than 700°C, on the other hand, the substrate is thermally damaged to disadvantageously separate the epitaxial layer which is formed thereon.
According to the present invention, the method (hereinafter referred to as "organic metal chloride vapor phase epitaxy") of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into the reaction chamber while heating the overall reaction chamber from the exterior for making vapor phase epitaxy on the substrate which is set in the reaction chamber is employed for forming the GaN buffer layer and the GaN
epitaxial layer. This organic metal chloride vapor phase epitaxy is at a high growth rate, and can obtain a steep hetero interface.
Furthermore, according to the present invention, the buffer layer and the epitaxial layer are formed by the same organic metal chloride vapor phase epitaxy.
Thus, these layers can be consistently formed in the same chamber.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
In the drawings, which illustrate embodiments of the invention, Figure 1 is a sectional view showing an exemplary structure of a compound semiconductor light emitting device according to the present invention;
Figure 2 schematically illustrates the structure of a vapor phase epitaxy device employed for preparing a compound semiconductor light emitting device through organic metal chloride vapor phase epitaxy according to the present invention;
Figure 3 illustrates the relationship between the thicknesses of GaN buffer layers and full width half maximums (FWHM) of X-ray peaks of GaN epitaxial layers;
Figure 4 illustrates the relationship between the thicknesses of the GaN
layers and surface irregularities of the GaN epitaxial layers;
Figure 5 is a sectional view showing an exemplary structure of a conventional blue and green light emitting device;
Figure 6 is a sectional view showing an exemplary structure of a conventional epitaxial wafer; and Figure 7 is a sectional view showing another exemplary structure of the conventional epitaxial wafer.
(Example 1 ) Figure 1 is a sectional view showing an exemplary structure of a compound semiconductor light emitting device according to the present invention.
Referring to Figure 1, a light emitting layer 4 consisting of Ino.2Gao.8N and a clad layer 5 consisting of p-type GaN are successively formed on an epitaxial wafer formed by a GaAs substrate 1, a buffer layer 2 consisting of GaN which is formed on the substrate 1, and an epitaxial layer 3 consisting of cubic n-type GaN which is formed on the buffer layer 2 in this blue light emitting device. Electrodes 6 and 7 are formed on an upper part of the clad layer 5 and a rear surface of the substrate 1 respectively. Further, an incommensurate plane 8 is located on the interface between the buffer layer 2 and the epitaxial layer 3.
A method of preparing the blue light emitting device having the aforementioned structure is now described.
Figure 2 schematically illustrates the structure of a vapor phase epitaxy device which is employed for preparing an epitaxial wafer through organic metal chloride vapor phase epitaxy according to the present invention. Referring to Figure 2, this device consists of a reaction chamber 54 having first and second gas inlet ports 51 and 52, an exhaust port 53, and a resistance heater 55 for heating the overall reaction chamber 54 from the exterior.
With the device having the aforementioned structure, a blue light emitting device was prepared in the following manner:
Referring to Figure 2, a gallium arsenide (GaAs) (100) plane substrate 1 which was pretreated with an ordinary HZS04 etching solution was first set in the reaction chamber 54 of quartz.
Then, the overall reaction chamber 54 was heated with the resistance heater 55 from the exterior to maintain the substrate 1 at a temperature of 500°C, for introducing trimethylgallium (TMGa) and hydrogen chloride (HCI) as group III
raw materials from the first gas inlet port 51 at partial pressures of 8 x 10~' atm. and 8 x 10-4 atm. respectively, while introducing ammonia gas (NH3) as a group V raw material from the second gas inlet port 52 at a partial pressure of 1.6 x 10-' atm.
Under such 5 conditions, epitaxy was made for 15 minutes, thereby forming a buffer layer consisting of n-type GaN having a thickness of 30 nm. Due to such interposition of the buffer layer 2, it was possible to remarkably improve crystallinity of an epitaxial layer which was formed thereon.
Then, the temperature ofthe substrate 1 which was provided with the buffer 10 layer 2 consisting of n-type GaN was increased by the resistance heater 55 to 750°C
to 800°C, and thereafter epitaxy was made for 60 minutes under such conditions that partial pressures of TMGa, HCI and NH3 were 8 x 10~ atm., 8 x 10~ atm. and 1.6 x 10-' atm. respectively.
Consequently, a mirror-faced n-type GaN epitaxial layer 3 of 2 ,um in thickness was formed on the buffer layer 2.
Then, the temperature of the substrate 1 which was provided with the buffer layer 2 and the epitaxial layer 3 was reduced to the range of 500°C to 700°C by the resistance heater 55, TMGa, trimethylindium (TMIn), HCI and NH3 were introduced under such conditions that the partial pressure of TMIn was 10 times that of TMGa, and epitaxy was made for 10 minutes.
Consequently, a light emitting layer 4 consisting of Ino.2Gao.8N was formed on the epitaxial layer 3.
Then, the conditions were returned to those for forming the epitaxial layer 3 consisting of n-type GaN, and a clad layer 5 consisting of p-type GaN was formed in a similar manner to the above.
The dopant for the n-type GaN layer was prepared from Si or S, and that for the p-type GaN layer was prepared from Mg. Further, the dopant for the n-type InGaN layer was prepared from Si or S, and that for the n-type InGaN layer was prepared from Zn.
Then, electrodes 6 and 7 were formed on the clad layer 5 and on the rear surface of the substrate 1 respectively, thereby completing a blue light emitting device.
It was confirmed that the blue light emitting device obtained in the aforementioned manner exhibits high performance.
When the partial pressure of TMIn was adjusted to be 20 times that of TMGa, a light emitting layer 4 consisting of Ino.SGao.SN was formed under the same conditions. The light emitting layerwas not doped. Consequently, a blue light emitting device having superior wavelength purity to the aforementioned device provided with the light emitting layer of Ino.2Gao,8N was obtained.
When the partial pressure of TMIn was adjusted to be 50 times that of TMGa and the substrate temperature was adjusted in the range of 450°C
to 650°C, a light emitting layer 4 consisting of Ina.BGao.2N was formed under the same conditions.
Ino.BGao.2N was not doped. Consequently, a green light emitting device having excellent wavelength purity was obtained.
(Example 2) A buffer layer 2 consisting of n-type GaN having a thickness of 30 nm was formed on a GaAs (100) plane substrate 1 using the same method described in Example 1.
Then, the temperature of the substrate 1 provided with the buffer layer 2 was increased to the range of 800°C to 850°C by the resistance heater 55, and thereafter TMGa, trimethylaluminum (TMAI), HCI and NH3 were introduced so that TMGa and TMAI were at equal partial pressure ratios to each other, for making epitaxy for 10 minutes.
Consequently, an epitaxial layer 3 consisting of n-type AIo.,Gao.9N was formed on the buffer layer 2.
Then, the temperature of the substrate 1 provided with the buffer layer 2 and the epitaxial layer 3 was reduced in the range of 500°C to 700°C by the resistance heater 55, and thereafter TMGa, TMIn, HCI and NH3 were introduced so that the partial pressure of TMIn was 10 times that of TMGa, for making epitaxy for 10 minutes.
Consequently, a light emitting layer 4 consisting of Ino.2Gao.8N was formed on the epitaxial layer 3.
Then, the conditions were returned to those for forming the epitaxial layer 3 consisting of n-type AIo,,Gao,9N, and a clad layer 5 consisting of p-type AIo,,Gao.9N
was formed in a similar manner to the above.
The dopant for the n-type AIGaN layer was prepared from Si or S, and that for the p-type AIGaN layer was prepared from Mg. Further, the dopant for the n-type InGaN layer was prepared from Si or S, and that for the n-type InGaN layer was prepared from Zn.
Then, electrodes 6 and 7 were formed on the clad layer 5 and on the rear surface of the substrate 1 respectively, thereby completing a blue light emitting device.
It was confirmed that the blue light emitting device obtained in the aforementioned manner exhibits high performance.
When the partial pressure of TMIn was adjusted to be 20 times that of TMGa, a light emitting layer 4 consisting of Ino.SGao.SN was formed under the same conditions. The light emitting layerwas not doped. Consequently, a blue light emitting device having superior wavelength purity to the device provided with the light emitting layer of Ino.2Gao,8N was obtained.
When the partial pressure of TMIn was adjusted to be 50 times that of TMGa and the substrate temperature was adjusted in the range of 450°C
to 650°C, a light emitting layer 4 consisting of Ino.BGao.2N was formed under the same conditions.
Ino.BGao.2N was not doped. Consequently, a green light emitting device having excellent wavelength purity was obtained.
(Comparative Example 1 ) In order to examine the difference between characteristics of epitaxial layers consisting of AIXGa,_XN (0 s x < 1 ) resulting from the presence/absence of buffer layers consisting of GaN, an epitaxial layer consisting of AIXGa,_xN (0 s x <
1 ) was directly grown on a GaAs substrate, under growth conditions similar to those of Example 1.
Consequently, it was observed that the surface of the GaAs substrate was damaged by a high temperature and irregularized such that the epitaxial layer formed thereon was separated from the substrate when no buffer layer consisting of GaN was provided.
In order to compare the different characteristics resulting from the presence/absence of the buffer layers with each other, results of measurement of irregularities on AIxGa,_XN epitaxial layers with a surface roughness meter, X-ray diffraction and PL measurement were compared with each other so as to evaluate the epitaxial wafers obtained in Example 1 and Comparative Example 1.
Consequently, a remarkable difference was observed as to the irreg ularities of the epitaxial layer surfaces, and it has been recognized that surface homology is remarkably improved due to provision of the buffer layer consisting of GaN.
Also as to the results of X-ray diffraction and PL measurement, extremely sharp peaks were observed only for the Example provided that the buffer layer was present.
(Example 3) In order to study the optimum thickness of the GaN buffer layer, GaN buffer layers of various thicknesses were formed on GaAs substrates, and GaN
epitaxial layers were grown thereon for measuring characteristics of the obtained GaN
epitaxial layers.
The GaN buffer layers and the GaN epitaxial layers were grown under conditions similar to those of Example 1.
Figure 3 illustrates the relationship between the thicknesses of the GaN
buffer layers and full width half maximums (FWHM) of X-ray peaks of the GaN
epitaxial layers. Referring to Figure 3, the axis of abscissas shows the thicknesses (nm) of the GaN buffer layers, and the axis of ordinates shows the full width half maximums (FWHM) (min.) of the X-ray peaks.
Figure 4 illustrates the relationship between the thicknesses of the GaN
buffer layers and the surface irregularities of the GaN epitaxial layers.
Referring to Figure 4, the axis of abscissas shows the thicknesses (nm) of the GaN buffer layers, and the axis of ordinates shows the surface irregularities (~cm). The surface irregularities are defined by the difFerences between uppermost points of convex portions and lowermost points of concave portions.
It is clearly understood from Figures 3 and 4 that crystallinity of the GaN
epitaxial layer which is grown on the bufFer layer is disadvantageously reduced if the thickness of the buffer layer is too small or too large. Thus, it is understood that the thickness of the GaN buffer layer is preferably 10 nm to 80 nm, and more preferably 20 nm to 60 nm.
It has been confirmed that a similar effect is attained also when a GaP, InAs or InP substrate is employed in place of the GaAs substrate.
It has also been confirmed that a similar effect is attained also when triethylgallium (TEGa) is employed as the group III raw material in place of TMGa.
(Example 4) A compound semiconductor light emitting device was prepared similarly to Example 1, by employing Mg as a dopant for an InGaN layer in place of Si, S or Zn.
Other preparation conditions were absolutely similar to those of Example 1, and hence redundant description is omitted.
Consequently, a violet light emitting device having a light emitting layer consisting of InyGa,_yN (0 < y < 1 ) which was doped with Mg was completed. It has been confirmed that the violet light emitting device obtained in the aforementioned manner exhibits high performance.
This violet light emitting device is absolutely similar in structure to Example 1 shown in Figure 1 except that the light emitting layer 4 consists of Ino.2Gao.8N which is doped with Mg, and hence redundant description is omitted.
When the partial pressure of TMIn was adjusted to be 20 times that of TMGa, a light emitting layer 4 consisting of Ino.SGaa.SN doped with Mg was formed under the same conditions. Consequently, it was confirmed that a blue light emitting device of high performance was obtained.
When the partial pressure of TMIn was adjusted to be 50 times that of TMGa and the substrate temperature was adjusted in the range of 450°C
to 650°C, a light emitting layer 4 consisting of Ino.$Gao.2N doped with Mg was formed under the same conditions. Consequently, it was confirmed that a green light emitting device of high performance was obtained.
(Example 5) A compound semiconductor light emitting device was prepared similarly to 5 Example 2, by employing Mg as a dopant for an InGaN layer in place of Si, S
or Zn.
At the time of growing a light emitting layer consisting of InGaN, TMGa, TMIn, HCI and NH3 were introduced so that the partial pressure of TMIn was 20 times that of TMGa.
Other preparation conditions were absolutely similar to those of Example 2, and hence redundant description is omitted.
10 Consequently, a blue light emitting device provided with a light emitting layer consisting of Ino.SGao.SN which was doped with Mg was completed. It has been confirmed that the blue light emitting device obtained in the aforementioned manner exhibits high performance.
When the partial pressure of TMIn was adjusted to be 50 times that of 15 TMGa in the InGaN layer and the substrate temperature was adjusted in the range of 450°C to 650°C, a light emitting layer 4 consisting of Ino.BGao.zN doped with Mg was formed under the same conditions. Consequently, it was confirmed that a green light emitting device of high performance was obtained.
According to the present invention, as hereinabove described, a compound semiconductor light emitting device of high performance can be readily prepared with a substrate of GaAs, GaP, InAs or InP at a low cost. In particular, band-edge emission can be implemented by Mg doping, whereby wide-ranging application to a laser diode etc. is enabled.
Further, the method according to the present invention is sufficiently applicable to industrial production.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, and the spirit and scope of the present invention is limited only by the terms of the appended claims.
According to the present invention, the gaN buffer layer which is formed at a lower temperature than the gaN epitaxial layer serves as such a heat-resistant coating.
The thickness of this GaN buffer layer is 10 nm to 80 nm. If the thickness is smaller than 10 nm, the buffer layer is partially broken during temperature increase for forming the epitaxial layer, to inevitably separate the epitaxial layer which is formed thereon. If the thickness is larger than 80 nm, on the other hand, nuclear growth is mixed into low-temperature growth of a flat buffer layer, to disadvantageously grow the epitaxial layer in the form of a pyramid about such nucleus.
According to the present invention, band-edge emission can be implemented when the light emitting layer consists of InyGa,_yN (0 < y < 1) which is doped with Mg.
In the conventional blue and green light emitting device, the emission wavelength is broad since blue emission is attained by introducing a deep center of Zn as an emission center. According to the present invention, on the other hand, formation of a GaInN layer of high In composition is enabled by employing a substrate of GaAs, GaP, InAs or InP. Consequently, band-edge emission having a sharp emission wavelength can be implemented by Mg doping, thereby enabling wide-ranging application to a laser diode and the like.
According to the inventive method of preparing a compound semiconductor light emitting device, the GaN buffer layer is formed on the substrate of the compound semiconductor which is selected from the group consisting of GaAs, GaP, InAs and InP at a temperature lower than the growth temperature of the GaN epitaxial layer.
Therefore, a cubic GaN epitaxial layer of high quality can be grown with no damage on the substrate crystals.
The temperature for forming the buffer layer consisting of GaN is preferably 300°C to 700°C. If the temperature is lower than 300°C, no buffer layer consisting of GaN is grown. If the temperature is higher than 700°C, on the other hand, the substrate is thermally damaged to disadvantageously separate the epitaxial layer which is formed thereon.
According to the present invention, the method (hereinafter referred to as "organic metal chloride vapor phase epitaxy") of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into the reaction chamber while heating the overall reaction chamber from the exterior for making vapor phase epitaxy on the substrate which is set in the reaction chamber is employed for forming the GaN buffer layer and the GaN
epitaxial layer. This organic metal chloride vapor phase epitaxy is at a high growth rate, and can obtain a steep hetero interface.
Furthermore, according to the present invention, the buffer layer and the epitaxial layer are formed by the same organic metal chloride vapor phase epitaxy.
Thus, these layers can be consistently formed in the same chamber.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
In the drawings, which illustrate embodiments of the invention, Figure 1 is a sectional view showing an exemplary structure of a compound semiconductor light emitting device according to the present invention;
Figure 2 schematically illustrates the structure of a vapor phase epitaxy device employed for preparing a compound semiconductor light emitting device through organic metal chloride vapor phase epitaxy according to the present invention;
Figure 3 illustrates the relationship between the thicknesses of GaN buffer layers and full width half maximums (FWHM) of X-ray peaks of GaN epitaxial layers;
Figure 4 illustrates the relationship between the thicknesses of the GaN
layers and surface irregularities of the GaN epitaxial layers;
Figure 5 is a sectional view showing an exemplary structure of a conventional blue and green light emitting device;
Figure 6 is a sectional view showing an exemplary structure of a conventional epitaxial wafer; and Figure 7 is a sectional view showing another exemplary structure of the conventional epitaxial wafer.
(Example 1 ) Figure 1 is a sectional view showing an exemplary structure of a compound semiconductor light emitting device according to the present invention.
Referring to Figure 1, a light emitting layer 4 consisting of Ino.2Gao.8N and a clad layer 5 consisting of p-type GaN are successively formed on an epitaxial wafer formed by a GaAs substrate 1, a buffer layer 2 consisting of GaN which is formed on the substrate 1, and an epitaxial layer 3 consisting of cubic n-type GaN which is formed on the buffer layer 2 in this blue light emitting device. Electrodes 6 and 7 are formed on an upper part of the clad layer 5 and a rear surface of the substrate 1 respectively. Further, an incommensurate plane 8 is located on the interface between the buffer layer 2 and the epitaxial layer 3.
A method of preparing the blue light emitting device having the aforementioned structure is now described.
Figure 2 schematically illustrates the structure of a vapor phase epitaxy device which is employed for preparing an epitaxial wafer through organic metal chloride vapor phase epitaxy according to the present invention. Referring to Figure 2, this device consists of a reaction chamber 54 having first and second gas inlet ports 51 and 52, an exhaust port 53, and a resistance heater 55 for heating the overall reaction chamber 54 from the exterior.
With the device having the aforementioned structure, a blue light emitting device was prepared in the following manner:
Referring to Figure 2, a gallium arsenide (GaAs) (100) plane substrate 1 which was pretreated with an ordinary HZS04 etching solution was first set in the reaction chamber 54 of quartz.
Then, the overall reaction chamber 54 was heated with the resistance heater 55 from the exterior to maintain the substrate 1 at a temperature of 500°C, for introducing trimethylgallium (TMGa) and hydrogen chloride (HCI) as group III
raw materials from the first gas inlet port 51 at partial pressures of 8 x 10~' atm. and 8 x 10-4 atm. respectively, while introducing ammonia gas (NH3) as a group V raw material from the second gas inlet port 52 at a partial pressure of 1.6 x 10-' atm.
Under such 5 conditions, epitaxy was made for 15 minutes, thereby forming a buffer layer consisting of n-type GaN having a thickness of 30 nm. Due to such interposition of the buffer layer 2, it was possible to remarkably improve crystallinity of an epitaxial layer which was formed thereon.
Then, the temperature ofthe substrate 1 which was provided with the buffer 10 layer 2 consisting of n-type GaN was increased by the resistance heater 55 to 750°C
to 800°C, and thereafter epitaxy was made for 60 minutes under such conditions that partial pressures of TMGa, HCI and NH3 were 8 x 10~ atm., 8 x 10~ atm. and 1.6 x 10-' atm. respectively.
Consequently, a mirror-faced n-type GaN epitaxial layer 3 of 2 ,um in thickness was formed on the buffer layer 2.
Then, the temperature of the substrate 1 which was provided with the buffer layer 2 and the epitaxial layer 3 was reduced to the range of 500°C to 700°C by the resistance heater 55, TMGa, trimethylindium (TMIn), HCI and NH3 were introduced under such conditions that the partial pressure of TMIn was 10 times that of TMGa, and epitaxy was made for 10 minutes.
Consequently, a light emitting layer 4 consisting of Ino.2Gao.8N was formed on the epitaxial layer 3.
Then, the conditions were returned to those for forming the epitaxial layer 3 consisting of n-type GaN, and a clad layer 5 consisting of p-type GaN was formed in a similar manner to the above.
The dopant for the n-type GaN layer was prepared from Si or S, and that for the p-type GaN layer was prepared from Mg. Further, the dopant for the n-type InGaN layer was prepared from Si or S, and that for the n-type InGaN layer was prepared from Zn.
Then, electrodes 6 and 7 were formed on the clad layer 5 and on the rear surface of the substrate 1 respectively, thereby completing a blue light emitting device.
It was confirmed that the blue light emitting device obtained in the aforementioned manner exhibits high performance.
When the partial pressure of TMIn was adjusted to be 20 times that of TMGa, a light emitting layer 4 consisting of Ino.SGao.SN was formed under the same conditions. The light emitting layerwas not doped. Consequently, a blue light emitting device having superior wavelength purity to the aforementioned device provided with the light emitting layer of Ino.2Gao,8N was obtained.
When the partial pressure of TMIn was adjusted to be 50 times that of TMGa and the substrate temperature was adjusted in the range of 450°C
to 650°C, a light emitting layer 4 consisting of Ina.BGao.2N was formed under the same conditions.
Ino.BGao.2N was not doped. Consequently, a green light emitting device having excellent wavelength purity was obtained.
(Example 2) A buffer layer 2 consisting of n-type GaN having a thickness of 30 nm was formed on a GaAs (100) plane substrate 1 using the same method described in Example 1.
Then, the temperature of the substrate 1 provided with the buffer layer 2 was increased to the range of 800°C to 850°C by the resistance heater 55, and thereafter TMGa, trimethylaluminum (TMAI), HCI and NH3 were introduced so that TMGa and TMAI were at equal partial pressure ratios to each other, for making epitaxy for 10 minutes.
Consequently, an epitaxial layer 3 consisting of n-type AIo.,Gao.9N was formed on the buffer layer 2.
Then, the temperature of the substrate 1 provided with the buffer layer 2 and the epitaxial layer 3 was reduced in the range of 500°C to 700°C by the resistance heater 55, and thereafter TMGa, TMIn, HCI and NH3 were introduced so that the partial pressure of TMIn was 10 times that of TMGa, for making epitaxy for 10 minutes.
Consequently, a light emitting layer 4 consisting of Ino.2Gao.8N was formed on the epitaxial layer 3.
Then, the conditions were returned to those for forming the epitaxial layer 3 consisting of n-type AIo,,Gao,9N, and a clad layer 5 consisting of p-type AIo,,Gao.9N
was formed in a similar manner to the above.
The dopant for the n-type AIGaN layer was prepared from Si or S, and that for the p-type AIGaN layer was prepared from Mg. Further, the dopant for the n-type InGaN layer was prepared from Si or S, and that for the n-type InGaN layer was prepared from Zn.
Then, electrodes 6 and 7 were formed on the clad layer 5 and on the rear surface of the substrate 1 respectively, thereby completing a blue light emitting device.
It was confirmed that the blue light emitting device obtained in the aforementioned manner exhibits high performance.
When the partial pressure of TMIn was adjusted to be 20 times that of TMGa, a light emitting layer 4 consisting of Ino.SGao.SN was formed under the same conditions. The light emitting layerwas not doped. Consequently, a blue light emitting device having superior wavelength purity to the device provided with the light emitting layer of Ino.2Gao,8N was obtained.
When the partial pressure of TMIn was adjusted to be 50 times that of TMGa and the substrate temperature was adjusted in the range of 450°C
to 650°C, a light emitting layer 4 consisting of Ino.BGao.2N was formed under the same conditions.
Ino.BGao.2N was not doped. Consequently, a green light emitting device having excellent wavelength purity was obtained.
(Comparative Example 1 ) In order to examine the difference between characteristics of epitaxial layers consisting of AIXGa,_XN (0 s x < 1 ) resulting from the presence/absence of buffer layers consisting of GaN, an epitaxial layer consisting of AIXGa,_xN (0 s x <
1 ) was directly grown on a GaAs substrate, under growth conditions similar to those of Example 1.
Consequently, it was observed that the surface of the GaAs substrate was damaged by a high temperature and irregularized such that the epitaxial layer formed thereon was separated from the substrate when no buffer layer consisting of GaN was provided.
In order to compare the different characteristics resulting from the presence/absence of the buffer layers with each other, results of measurement of irregularities on AIxGa,_XN epitaxial layers with a surface roughness meter, X-ray diffraction and PL measurement were compared with each other so as to evaluate the epitaxial wafers obtained in Example 1 and Comparative Example 1.
Consequently, a remarkable difference was observed as to the irreg ularities of the epitaxial layer surfaces, and it has been recognized that surface homology is remarkably improved due to provision of the buffer layer consisting of GaN.
Also as to the results of X-ray diffraction and PL measurement, extremely sharp peaks were observed only for the Example provided that the buffer layer was present.
(Example 3) In order to study the optimum thickness of the GaN buffer layer, GaN buffer layers of various thicknesses were formed on GaAs substrates, and GaN
epitaxial layers were grown thereon for measuring characteristics of the obtained GaN
epitaxial layers.
The GaN buffer layers and the GaN epitaxial layers were grown under conditions similar to those of Example 1.
Figure 3 illustrates the relationship between the thicknesses of the GaN
buffer layers and full width half maximums (FWHM) of X-ray peaks of the GaN
epitaxial layers. Referring to Figure 3, the axis of abscissas shows the thicknesses (nm) of the GaN buffer layers, and the axis of ordinates shows the full width half maximums (FWHM) (min.) of the X-ray peaks.
Figure 4 illustrates the relationship between the thicknesses of the GaN
buffer layers and the surface irregularities of the GaN epitaxial layers.
Referring to Figure 4, the axis of abscissas shows the thicknesses (nm) of the GaN buffer layers, and the axis of ordinates shows the surface irregularities (~cm). The surface irregularities are defined by the difFerences between uppermost points of convex portions and lowermost points of concave portions.
It is clearly understood from Figures 3 and 4 that crystallinity of the GaN
epitaxial layer which is grown on the bufFer layer is disadvantageously reduced if the thickness of the buffer layer is too small or too large. Thus, it is understood that the thickness of the GaN buffer layer is preferably 10 nm to 80 nm, and more preferably 20 nm to 60 nm.
It has been confirmed that a similar effect is attained also when a GaP, InAs or InP substrate is employed in place of the GaAs substrate.
It has also been confirmed that a similar effect is attained also when triethylgallium (TEGa) is employed as the group III raw material in place of TMGa.
(Example 4) A compound semiconductor light emitting device was prepared similarly to Example 1, by employing Mg as a dopant for an InGaN layer in place of Si, S or Zn.
Other preparation conditions were absolutely similar to those of Example 1, and hence redundant description is omitted.
Consequently, a violet light emitting device having a light emitting layer consisting of InyGa,_yN (0 < y < 1 ) which was doped with Mg was completed. It has been confirmed that the violet light emitting device obtained in the aforementioned manner exhibits high performance.
This violet light emitting device is absolutely similar in structure to Example 1 shown in Figure 1 except that the light emitting layer 4 consists of Ino.2Gao.8N which is doped with Mg, and hence redundant description is omitted.
When the partial pressure of TMIn was adjusted to be 20 times that of TMGa, a light emitting layer 4 consisting of Ino.SGaa.SN doped with Mg was formed under the same conditions. Consequently, it was confirmed that a blue light emitting device of high performance was obtained.
When the partial pressure of TMIn was adjusted to be 50 times that of TMGa and the substrate temperature was adjusted in the range of 450°C
to 650°C, a light emitting layer 4 consisting of Ino.$Gao.2N doped with Mg was formed under the same conditions. Consequently, it was confirmed that a green light emitting device of high performance was obtained.
(Example 5) A compound semiconductor light emitting device was prepared similarly to 5 Example 2, by employing Mg as a dopant for an InGaN layer in place of Si, S
or Zn.
At the time of growing a light emitting layer consisting of InGaN, TMGa, TMIn, HCI and NH3 were introduced so that the partial pressure of TMIn was 20 times that of TMGa.
Other preparation conditions were absolutely similar to those of Example 2, and hence redundant description is omitted.
10 Consequently, a blue light emitting device provided with a light emitting layer consisting of Ino.SGao.SN which was doped with Mg was completed. It has been confirmed that the blue light emitting device obtained in the aforementioned manner exhibits high performance.
When the partial pressure of TMIn was adjusted to be 50 times that of 15 TMGa in the InGaN layer and the substrate temperature was adjusted in the range of 450°C to 650°C, a light emitting layer 4 consisting of Ino.BGao.zN doped with Mg was formed under the same conditions. Consequently, it was confirmed that a green light emitting device of high performance was obtained.
According to the present invention, as hereinabove described, a compound semiconductor light emitting device of high performance can be readily prepared with a substrate of GaAs, GaP, InAs or InP at a low cost. In particular, band-edge emission can be implemented by Mg doping, whereby wide-ranging application to a laser diode etc. is enabled.
Further, the method according to the present invention is sufficiently applicable to industrial production.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, and the spirit and scope of the present invention is limited only by the terms of the appended claims.
Claims (15)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A compound semiconductor light emitting device including:
a substrate of a compound semiconductor being selected from the group of consisting of GaAs, GaP, InAs and InP;
a buffer layer consisting of GaN, having a thickness of 10 nm to 80 nm, being formed on said substrate;
an epitaxial layer consisting of Al x Ga1-x N(0 ~ x < 1) being formed on said buffer layer;
an incommensurate plane being located on the interface between said buffer layer and said epitaxial layer;
a light emitting layer being formed on said epitaxial layer; and a clad layer being formed on said light emitting layer.
a substrate of a compound semiconductor being selected from the group of consisting of GaAs, GaP, InAs and InP;
a buffer layer consisting of GaN, having a thickness of 10 nm to 80 nm, being formed on said substrate;
an epitaxial layer consisting of Al x Ga1-x N(0 ~ x < 1) being formed on said buffer layer;
an incommensurate plane being located on the interface between said buffer layer and said epitaxial layer;
a light emitting layer being formed on said epitaxial layer; and a clad layer being formed on said light emitting layer.
2. The compound semiconductor light emitting device in accordance with claim 1, wherein the thickness of said buffer layer is 20 nm to 60 nm.
3. The compound semiconductor light emitting device in accordance with claim 1, wherein said epitaxial layer consists of Al x Ga1-x N(0 ~ x < 1) having a first conductivity type;
said light emitting layer consists of In y Ga1-y N
(0 < y < 1); and said clad layer consists of Al z Ga1-z N (0 ~ z < 1) having a second conductivity type being different from said first conductivity type.
said light emitting layer consists of In y Ga1-y N
(0 < y < 1); and said clad layer consists of Al z Ga1-z N (0 ~ z < 1) having a second conductivity type being different from said first conductivity type.
4. The compound semiconductor light emitting device in accordance with claim 3, wherein the thickness of said buffer layer is 20 nm to 60 nm.
5. The compound semiconductor light emitting device in accordance with claim 3, wherein said light emitting layer consisting of In y Ga1-y N
(0 < y < 1) is doped with Mg.
(0 < y < 1) is doped with Mg.
6. The compound semiconductor light emitting device in accordance with claim 5, wherein the thickness of said buffer layer is 20 nm to 60 nm.
7. A method of preparing a compound semiconductor light emitting device, comprising the steps of:
forming a buffer layer consisting of GaN on a substrate of a compound semiconductor being selected from the group consisting of GaAs, GaP, InAs and InP
at a first temperature by a method of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into a reaction chamber while heating overall said reaction chamber from the exterior for making vapor phase epitaxy on said substrate being set in said reaction chamber;
forming an epitaxial layer consisting of Al x Ga1-x N
(0 ~ x < 1) on said buffer layer at a temperature being higher than said first temperature by said method of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into said reaction chamber while heating overall said reaction chamber from the exterior for making vapor phase epitaxy on said substrate being set in said reaction chamber;
forming a light emitting layer on said epitaxial layer; and forming a clad layer on said light emitting layer.
forming a buffer layer consisting of GaN on a substrate of a compound semiconductor being selected from the group consisting of GaAs, GaP, InAs and InP
at a first temperature by a method of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into a reaction chamber while heating overall said reaction chamber from the exterior for making vapor phase epitaxy on said substrate being set in said reaction chamber;
forming an epitaxial layer consisting of Al x Ga1-x N
(0 ~ x < 1) on said buffer layer at a temperature being higher than said first temperature by said method of introducing a first gas including an organic metal raw material containing hydrogen chloride and gallium and a second gas including ammonia into said reaction chamber while heating overall said reaction chamber from the exterior for making vapor phase epitaxy on said substrate being set in said reaction chamber;
forming a light emitting layer on said epitaxial layer; and forming a clad layer on said light emitting layer.
8. The method of preparing a compound semiconductor light emitting device in accordance with claim 7, wherein said first temperature is 300°C to 700°C, and said second temperature is at least 750°C.
9. The method of preparing a compound semiconductor light emitting device in accordance with claim 8, wherein said first temperature is 400°C to 600°C.
10. The method of preparing a compound semiconductor light emitting device in accordance with claim 7, wherein said epitaxial layer consists of Al x Ga1-x N (0 ~ x < 1) having a first conductivity type;
said light emitting layer consists of ln y Ga y-1N (0 < y < 1); and said clad layer consists of Al z Ga1-z N (0 ~ z < 1) having a second conductivity type being different from said first conductivity type.
said light emitting layer consists of ln y Ga y-1N (0 < y < 1); and said clad layer consists of Al z Ga1-z N (0 ~ z < 1) having a second conductivity type being different from said first conductivity type.
11. The method of preparing a compound semiconductor light emitting device in accordance with claim 10, wherein said first temperature is 300°C to 700°C, and said second temperature is at least 750°C.
12. The method of preparing a compound semiconductor light emitting device in accordance with claim 11, wherein said first temperature is 400°C to 600°C.
13. The method of preparing a compound semiconductor light emitting device in accordance with claim 10, wherein said light emitting layer consisting of ln y Ga1-y N (0 < y < 1) is doped with Mg.
14. The method of preparing a compound semiconductor light emitting device in accordance with claim 13, wherein said first temperature is 300°C to 700°C, and said second temperature is at least 750°C.
15. The method of preparing a compound semiconductor light emitting device in accordance with claim 14, wherein said first temperature is 400°C to 600°C.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6805195A JPH08264836A (en) | 1995-03-27 | 1995-03-27 | Light emitting compound semiconductor element and manufacture thereof |
| JP7-68047 | 1995-03-27 | ||
| JP7-68051 | 1995-03-27 | ||
| JP6804795A JPH08264835A (en) | 1995-03-27 | 1995-03-27 | Light emitting compound semiconductor element and manufacture thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2170922A1 CA2170922A1 (en) | 1996-09-28 |
| CA2170922C true CA2170922C (en) | 2000-02-01 |
Family
ID=26409291
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002170922A Expired - Fee Related CA2170922C (en) | 1995-03-27 | 1996-03-04 | Compound semiconductor light emitting device and method of preparing the same |
Country Status (6)
| Country | Link |
|---|---|
| US (2) | US5665986A (en) |
| EP (1) | EP0735598A3 (en) |
| KR (1) | KR960036160A (en) |
| CN (1) | CN1082255C (en) |
| CA (1) | CA2170922C (en) |
| TW (1) | TW290743B (en) |
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|---|---|---|---|---|
| US5909040A (en) * | 1994-03-09 | 1999-06-01 | Kabushiki Kaisha Toshiba | Semiconductor device including quaternary buffer layer with pinholes |
| JP3771952B2 (en) * | 1995-06-28 | 2006-05-10 | ソニー株式会社 | Method for growing single crystal III-V compound semiconductor layer, method for manufacturing light emitting element, and method for manufacturing transistor |
| JPH0983017A (en) * | 1995-09-08 | 1997-03-28 | Sumitomo Electric Ind Ltd | Epitaxial wafer and production thereof |
| JP2925004B2 (en) * | 1996-03-22 | 1999-07-26 | 日本電気株式会社 | Gallium nitride crystal growth method |
| JP3164016B2 (en) * | 1996-05-31 | 2001-05-08 | 住友電気工業株式会社 | Light emitting device and method for manufacturing wafer for light emitting device |
| US6030848A (en) * | 1996-06-28 | 2000-02-29 | Kabushiki Kaisha Toshiba | Method for manufacturing a GaN-based compound semiconductor light emitting device |
| US5684309A (en) * | 1996-07-11 | 1997-11-04 | North Carolina State University | Stacked quantum well aluminum indium gallium nitride light emitting diodes |
| JPH111399A (en) * | 1996-12-05 | 1999-01-06 | Lg Electron Inc | Production of gallium nitride semiconductor single crystal substrate and gallium nitride diode produced by using the substrate |
| US6091083A (en) * | 1997-06-02 | 2000-07-18 | Sharp Kabushiki Kaisha | Gallium nitride type compound semiconductor light-emitting device having buffer layer with non-flat surface |
| DE19725900C2 (en) * | 1997-06-13 | 2003-03-06 | Dieter Bimberg | Process for the deposition of gallium nitride on silicon substrates |
| US6559467B2 (en) * | 1997-11-18 | 2003-05-06 | Technologies And Devices International, Inc. | P-n heterojunction-based structures utilizing HVPE grown III-V compound layers |
| JP4166885B2 (en) | 1998-05-18 | 2008-10-15 | 富士通株式会社 | Optical semiconductor device and manufacturing method thereof |
| US6194742B1 (en) * | 1998-06-05 | 2001-02-27 | Lumileds Lighting, U.S., Llc | Strain engineered and impurity controlled III-V nitride semiconductor films and optoelectronic devices |
| KR100495215B1 (en) * | 2002-12-27 | 2005-06-14 | 삼성전기주식회사 | VERTICAL GaN LIGHT EMITTING DIODE AND METHOD OF PRODUCING THE SAME |
| JP3841092B2 (en) | 2003-08-26 | 2006-11-01 | 住友電気工業株式会社 | Light emitting device |
| JP2005191530A (en) * | 2003-12-03 | 2005-07-14 | Sumitomo Electric Ind Ltd | Light emitting device |
| US7872268B2 (en) * | 2004-04-22 | 2011-01-18 | Cree, Inc. | Substrate buffer structure for group III nitride devices |
| CN101656288B (en) * | 2005-07-06 | 2013-06-12 | Lg伊诺特有限公司 | Nitride semiconductor led |
| CN100550443C (en) * | 2005-07-06 | 2009-10-14 | Lg伊诺特有限公司 | Nitride semiconductor LED and manufacture method thereof |
| US7585769B2 (en) * | 2006-05-05 | 2009-09-08 | Applied Materials, Inc. | Parasitic particle suppression in growth of III-V nitride films using MOCVD and HVPE |
| TWI309439B (en) * | 2006-09-05 | 2009-05-01 | Ind Tech Res Inst | Nitride semiconductor and method for forming the same |
| US9064706B2 (en) * | 2006-11-17 | 2015-06-23 | Sumitomo Electric Industries, Ltd. | Composite of III-nitride crystal on laterally stacked substrates |
| US20100025796A1 (en) * | 2008-08-04 | 2010-02-04 | Amir Massoud Dabiran | Microchannel plate photocathode |
| JP5378829B2 (en) * | 2009-02-19 | 2013-12-25 | 住友電気工業株式会社 | Method for forming epitaxial wafer and method for manufacturing semiconductor device |
| JP5776021B2 (en) * | 2010-04-02 | 2015-09-09 | パナソニックＩｐマネジメント株式会社 | Nitride-based semiconductor device and light source |
| DE102011002145B4 (en) * | 2011-04-18 | 2023-02-09 | Aixtron Se | Device and method for large-area deposition of semiconductor layers with gas-separated HCl feed |
| DE102011002146B4 (en) | 2011-04-18 | 2023-03-09 | Aixtron Se | Apparatus and method for depositing semiconductor layers with HCI addition to suppress parasitic growth |
| CN103258722A (en) * | 2013-04-27 | 2013-08-21 | 中国电子科技集团公司第十三研究所 | Method adopting AlGaInN buffering layer to grow three-group nitride in GaAs substrate |
| CN106328771B (en) * | 2015-07-04 | 2018-08-17 | 东莞市中镓半导体科技有限公司 | A method of the extension flawless high-crystal quality LED epitaxial layers in nitride metal gallium compound substrate |
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|---|---|---|---|---|
| US5218216A (en) * | 1987-01-31 | 1993-06-08 | Toyoda Gosei Co., Ltd. | Gallium nitride group semiconductor and light emitting diode comprising it and the process of producing the same |
| US5278433A (en) * | 1990-02-28 | 1994-01-11 | Toyoda Gosei Co., Ltd. | Light-emitting semiconductor device using gallium nitride group compound with double layer structures for the n-layer and/or the i-layer |
| US5281830A (en) * | 1990-10-27 | 1994-01-25 | Toyoda Gosei Co., Ltd. | Light-emitting semiconductor device using gallium nitride group compound |
| JPH088217B2 (en) * | 1991-01-31 | 1996-01-29 | 日亜化学工業株式会社 | Crystal growth method for gallium nitride-based compound semiconductor |
| EP0576566B1 (en) * | 1991-03-18 | 1999-05-26 | Trustees Of Boston University | A method for the preparation and doping of highly insulating monocrystalline gallium nitride thin films |
| JP3155007B2 (en) * | 1991-07-05 | 2001-04-09 | 三菱化学株式会社 | Compound semiconductor and manufacturing method thereof |
| JP2666228B2 (en) * | 1991-10-30 | 1997-10-22 | 豊田合成株式会社 | Gallium nitride based compound semiconductor light emitting device |
| US5400740A (en) * | 1992-02-06 | 1995-03-28 | Mitsubishi Chemical Corporation | Method of preparing compound semiconductor |
| JP3247437B2 (en) * | 1992-03-10 | 2002-01-15 | 旭化成株式会社 | Nitride-based semiconductor device and method of manufacturing the same |
| US5578839A (en) * | 1992-11-20 | 1996-11-26 | Nichia Chemical Industries, Ltd. | Light-emitting gallium nitride-based compound semiconductor device |
| US5523589A (en) * | 1994-09-20 | 1996-06-04 | Cree Research, Inc. | Vertical geometry light emitting diode with group III nitride active layer and extended lifetime |
-
1996
- 1996-02-23 TW TW085102056A patent/TW290743B/zh not_active IP Right Cessation
- 1996-03-04 CA CA002170922A patent/CA2170922C/en not_active Expired - Fee Related
- 1996-03-07 US US08/614,837 patent/US5665986A/en not_active Expired - Lifetime
- 1996-03-07 EP EP96103584A patent/EP0735598A3/en not_active Withdrawn
- 1996-03-12 KR KR1019960006429A patent/KR960036160A/en not_active Application Discontinuation
- 1996-03-27 CN CN96104423A patent/CN1082255C/en not_active Expired - Fee Related
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1997
- 1997-05-15 US US08/856,911 patent/US5756374A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CN1137690A (en) | 1996-12-11 |
| EP0735598A3 (en) | 1998-09-23 |
| US5665986A (en) | 1997-09-09 |
| US5756374A (en) | 1998-05-26 |
| EP0735598A2 (en) | 1996-10-02 |
| CN1082255C (en) | 2002-04-03 |
| CA2170922A1 (en) | 1996-09-28 |
| TW290743B (en) | 1996-11-11 |
| KR960036160A (en) | 1996-10-28 |
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